Container inspection apparatus having diameter measuring means and associated method

ABSTRACT

Apparatus for inspecting non-round annular containers includes elongated capacitive sensors, cooperating oscillators, which convert the sensor signal to a voltage corresponding thereto, and an electronic processor which receives the voltage and determines thickness. A displaceable electromechanical member is operatively associated with the sensor and emits an electrical signal corresponding to the degree of displacement of the sensor by a container being inspected. The electronic processor corrects the thickness determination by an adjustment of container diameter at the specific location where thickness is being monitored in order to compensate for container diameter variations due to the non-round characteristic of the container. In a preferred embodiment, linkage members secured to the rear of the sensor at a plurality of locations cooperate with a single displaceable element which converts the mechanical displacement of the sensor into a corresponding electrical signal. Movement between the capacitive sensors and the apparatus urging the containers into intimate contact therewith to accommodate variations in container diameter, while maintaining intimacy of sensor-container contact, is provided. The sensors and/or apparatus for urging the containers into intimate contact may be resiliently mounted. In one embodiment, sensors may be placed on both sides of the path of travel of the container which will have its diameter monitored on both sides thereby permitting rotation of the container against the sensors through 180° rather than 360°. A corresponding method is provided.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a system for measuring the wallthickness of generally oval shaped containers and, more specifically,includes means for adjusting the thickness measurement for changes indiameter resulting from the non-round nature of the container. Theinvention also relates to measurement of container diameters.

2. Description of the Prior Art

It has long been known, with respect to containers, such as glass andplastic bottles and jars, to inspect the same for compliance withvarious specifications, such as shape, dimensions, wall thickness, andany other departures from the specified parameters. In connection withsuch inspection, it has been known to use a sampling technique whereinperiodically a sample container is removed from the production line andinspected. For glass containers, the measurement of thickness, forexample, has been accomplished by hand-held capacitive or ultrasonicthickness measuring instruments. In the alternate, destructive testingas by taking a sample and cutting it into pieces with subsequentmechanical measurement has also been known. While such samplingtechniques can provide accurate measurements, they suffer from thedisadvantage of using samples and the need to make statisticalinferences based upon the results of such sampling. As every containeris not inspected, it is possible that a number of defects will goundetected. This can result not only in loss of the container, but lossof the product to be placed in the container and, perhaps, injury to theconsumer or other user.

It has been known to employ capacitive means for automaticallyinspecting wall thickness of containers made of dielectric materialswith inspection of each container, as distinguished from samplingtechniques, being employed. See, generally, U.S. Pat. Nos. 2,573,824;4,820,972; 4,862,062; 4,870,342; 4,930,364; 4,965,523; and 4,972,566. Ithas also been known, in such a context, to provide a plurality ofsensors which cooperate with oscillator means to produce an outputvoltage responsive to capacitance changes which voltage is employed todetermine container wall thickness. See, for example, U.S. Pat. Nos.4,862,062; 4,870,342; 4,965,523; and 4,972,566.

It has also been known to provide such a system wherein a plurality ofcontainers rotating by and being urged into intimate contact with aplurality of sensors may be inspected simultaneously. See U.S. Pat. No.5,097,216 which is owned by the assignee of the present application.

These prior systems were directed toward inspecting round containersmade of a dielectric material. When non-round annular containers, suchas oval containers, for example, are to be inspected, these systems arenot readily applicable.

There remains, therefore, a real and substantial need for an automatedmeans of rapidly inspecting dielectric containers which have a generallyoval configuration.

SUMMARY OF THE INVENTION

The present invention has met the above-described need by providing asystem wherein elongated capacitive sensor means serve to provide outputsignals which are converted into voltage signals and, ultimately, athickness reading and corresponding mechanical means serve to deform adisplaceable element responsive to a container deforming the sensormeans so as to provide a voltage signal which may be employed todetermine diameter changes and provide a corresponding correction for athickness reading related to the diameter of the container at theposition where thickness has been measured.

In a preferred practice of the invention, a linkage means will besecured to the rear of the sensor means and be associated with atransducer which will be displaced responsive to container induceddeformation of the sensor means. The transducer output is employed toprovide information from which the container diameter is determined. Thediameter provides a means for adjusting the wall thickness reading.

In a preferred practice of the invention, the sensor means will emit asignal which will be converted to a corresponding voltage signal relatedto thickness by oscillator means which voltage signal will be receivedby electronic processor means, which makes a comparison of the measuredthickness with stored, desired thickness values and determines whetherthe desired thickness is present. The displaceable diameter indicatingmeans, such as a transducer, also emits a signal which is received bythe electronic processor means and a determination of diametervariations is made which provides a correction factor for the thicknessvalue.

If desired, a plurality of elongated individual sensor means may beemployed.

A look-up table may be provided in the electronic processor means fordetermining the thickness correction factor to be employed for aparticular displacement of the transducer.

In another embodiment, sensor means may be positioned on both sides ofthe path of travel of the container and rather than having the containerrotate through 360° so as to permit substantially continuousdetermination of diameter and thickness about the circumference of thecontainer, each sensor means may be employed to determine approximately180° of measurement in the aggregate thereby minimizing the amount ofrotation of the container required.

A corresponding method is provided.

It is an object of the present invention to provide apparatus and anassociated method for efficiently measuring the wall thickness ofdielectric containers which are of non-round shape.

It is another object of the present invention to effect such inspectionin an automated rapid fashion which permits inspection of each containeras distinguished from employing a sampling technique.

It is a further object of the present invention to measure diameterchanges by mechanical movement of linkage means secured to the rear ofthe sensor means which emits a responsive electrical signal to beprocessed by the electronic processor means so as to adjust thethickness measurement for diameter changes where desired.

It is a further object of the invention to provide such a system whichis compatible with existing capacitive sensor measurement of wallthickness of dielectric containers.

It is a further object of the invention to provide a system whichprovides rapid on-line real time measurements of container thicknesscompensated for changes in diameter on non-round annular containers.

It is a further object of the present invention to provide a system formeasuring container diameters to detect variations therein.

It is a further object of the invention to provide such a system whichcan function with a single displacement receiving means which movesresponsive to container deformation of the sensor regardless of wherethe container is positioned on the sensor.

These and other objects of the present invention will be more fullyunderstood from the following description of the invention withreference to the illustrations appended hereto.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a top plan view of a container moving both translationally androtationally along the apparatus of the present invention.

FIG. 2 is a front elevational view showing the sensor means and acontainer in contact therewith.

FIG. 3 is a partially schematic illustration of a sensor of the presentinvention.

FIGS. 4 and 5 are respectively cross-sectional illustrations takenthrough FIGS. 4--4 and 5--5 of FIG. 3 showing portions of the sensormeans.

FIG. 6 is a rear elevational view of the sensor of FIG. 3.

FIG. 6a is a detail showing the electrical connector portion of thesensor.

FIG. 7 is a top plan view of a form of apparatus of the presentinvention.

FIG. 8 is a rear elevational view of the apparatus shown in FIG. 2.

FIG. 9 is a left-side elevational view of the apparatus shown in FIG. 2.

FIG. 10 is a right-side elevational view of the apparatus shown in FIG.2.

FIG. 11 is a bottom plan view of the apparatus of FIG. 2.

FIG. 12 shows a top plan view of a modified embodiment of the inventionemploying a sensor of reduced longitudinal extent.

FIG. 13 is a top plan view showing another embodiment of the inventionwherein sensor means are provided on both sides of the path of travel ofthe container.

FIG. 14 is a schematic illustration showing the manner in which signalsare delivered from various sensors to the electronic processor means.

FIG. 15 is a flow chart representative of a preferred practice of themethod of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to FIG. 1, there is shown a portion of an inspection systemusable in the present invention. The system has inspection station witha conveyor 4 moving a generally oval shaped container 10 to be inspectedtranslationally in the direction of the arrow A. The container 10 ismoved translationally and is also subjecting it to axial rotation bydriven belt 14 which also serves to urge the container 10 into intimatecontact with capacitive sensor means 12. It will be appreciated that thecapacitive sensors means 12, in a manner to be discussed in detailhereinafter, take readings either (a) at predetermined intervals or (b)continuously as the container rotates thereagainst in order to monitorwall thickness about substantially the entire circumference of container10. It will be appreciated that with oval containers, as they aresubjected to axial rotation, the effective diameter of the portion incontact with the sensor means 12 will vary. It is necessary tocompensate for variance in order to avoid distortion of the thicknessreading due to such diameter variations.

As used herein, the term "non-round annular" containers will refer tocontainers having the portion which is being inspected not of roundconfiguration and yet being annular in the sense of not having cornersthat would interfere with rolling action of the containers, such aswould occur with containers which are rectangular, triangular orpolygonal. It will expressly embrace oval-shaped containers and othernon-round containers capable of rolling along the sensing means forsequential inspection thereof.

Referring now to FIG. 2, additional details of the invention will beconsidered. In this embodiment, the container 20 is shown as a glass orplastic bottle, although it will be appreciated that the invention maybe employed with other dielectric containers, such as jars, for example.

The container 20 is moving in the direction indicated by arrow B and isbeing urged into intimate contact with the sensor means, which in theform shown, consists of four elongated sensors 22, 24, 26, 28 which aregenerally parallel to each other, extend along the direction of movementof container 20, and are relatively vertically spaced from each other.They also have their surfaces closest to the container 20 in generallyaligned position with respect to each other. As the container 20 movesrotationally and translationally in the direction of arrow B and isurged into intimate contact with the sensors 22, 24, 26, 28, readingswill be taken at each of the four levels containing the sensors 22, 24,26, 28. The container is being transported on conveyor 30. It will beappreciated that as the container progressively rotates on the sensors22, 24, 26, 28, the capacitance will change with the resultant voltageoutput corresponding thereto.

Referring to FIGS. 3 through 5, details of a sensor will be considered.The sensor 30 has a sensor strip 32 which, in the form shown, may becomposed of a dielectric material, such as a polyolefin, such aspolypropylene, for example. On the face of the sensor 32 is the sensingarea which will be in contact with the container being inspected. Asshown in FIG. 4, the region of the sensor strip 32 has an electricallyconductive surface, such as by applying an electrically conductive paintof a thickness of about 0.002 to 0.005 inch as by silk screening orspraying. As shown in FIGS. 4 and 5, the sensor 30, which may be a blockof a suitable dielectric material, has sensor area 32 covered with anelectrically conductive material and is surrounded by an uncoated regionwhich is a dielectric frame surrounding sensor element 32. Upper andlower portions 33, 34 of this dielectric frame are shown in FIG. 4. Theremainder of the surface of sensor 30 is also coated with anelectrically conductive material which is indicated generally byreference number 35. In this manner, sensor 32 serves as one plate ofthe capacitor and coated region 35 serves as the other plate of thecapacitor. The sensor 30 has an overlying tape member 36 which isadapted to resist sensor wear on the front face which contacts thecontainer. The tape member 36 may be made of a suitable dielectricmaterial which is sufficiently thin as to not interfere with thefunctioning of the sensor area. In FIG. 5, there is shown across-section of the sensor in a region which is entirely coated withthe conductive layer 34. The sensor area 32 is not present in this area.

FIGS. 6 and 6a shows the reverse side of sensor 32 and shows the recess40 in the reverse side of sensor 30 which contains the electricalcontacts for transmitting the output of sensor 30 to the otherprocessing means in the system. In order to minimize the weight of thesensor 30, the inductor 36, which is part of the tuned circuit, ispositioned within recess 40 and electrically connected by a suitablecable to the oscillator electronics which are not mounted on the sensor30. The inductor 36 has coils 37 and is connected as an autotransformer.One lead of the primary coil and one lead of the secondary coil aresecured to the oscillator cable connector 42 by leads 38, 39,respectively. Lead 39 is connected to the inner insulated contact 44 ofconnector 42. Lead 45 of inductor 36 is connected to sensor strip 32.The oscillator cable connector 42 through fasteners 46, 48 areelectrically connected to the larger painted area 35. In this manner,changes in capacitance caused by container inspection will betransmitted through oscillator cable connector 42 to the oscillatorelectronics for conversion to corresponding voltage signals.

Referring to FIGS. 7 through 11, additional details of the preferredembodiment of the invention will be considered. Referring in greaterdetail to FIG. 7, there is shown an oval container 46 being urged intocontact with capacitive sensor means 48 by belt 50. The container istraveling in the direction indicated by arrow C. In this embodiment, thesensor means 48 consists of four sensor elements with only the uppermostsensor 53 shown in this view. This sensor 53 has a sensor strip 52 whichis on the front face of sensor 53 and is in contact with the container46 and a back-up bar 54 which is secured to the sensor 53 throughresilient foam. It is desirable to have the sensor assembly 52, 53, 54be relatively lightweight and flexible. Secured to back-up bar 54 is apivotable linkage member 60 which is secured through suitable pivot pin62 to connector member 64 which connects the same to back-up bar 54.Fastener 66 of the linkage member 60 which, in the form shown, isgenerally triangular, serves as a pivot for the linkage member 60.Fastener 68 is rotatable responsive to rotational movement of thelinkage bar 60. In the form illustrated, if the container 46 were tohave an enlarged diameter portion come in contact with the sensor means48, at point P illustrated on the sensor 53, it would tend to deform thesensor means 48 in a direction generally downwardly with respect to FIG.7. This, in turn, would cause counter-clockwise rotation of the linkagemeans 60 in the direction indicated by arrow D.

Referring to sensor region 70 which is located upstream in respect ofthe direction of travel of container 46, attached thereto is a supportbracket 72 which is secured to back-up bar 54. Linkage member 76 is, inthe form shown, generally triangular in shape and has a pivot pin 78securing the same to bracket 72, a pivotal fastener 80, which is securedto a support member, and a fastener 82 which secures the linkage tolinkage bar 85 which connects linkage element 60 and 76.

It will be appreciated that when the container 46 deforms the sensor 52in a direction generally downwardly of the page, as shown in FIG. 7, thecounter-clockwise rotation of linkage element 60 about pivot 66 willcreate similar counter-clockwise rotation of linkage element 76 aboutpivot 80 in the direction indicated by arrow E. A displacement monitor84 which, in the form indicated is a transducer, has a movable element86 secured to linkage member 76 through pivot pin 78. In the examplegiven, therefore, an enlarged diameter portion of container 46 woulddeform the sensor 52 establishing counter-clockwise rotation of linkageelement 60 and through linkage connector 85 would create responsivecounter-clockwise rotation of linkage element 76 which, in turn, wouldmove the piston element 86 of displacement means 84 generally downwardlyin the direction indicated by arrow F. In the preferred embodiment, thedisplacement means 84 will be a transducer which will emit an electricalsignal which corresponds to the degree of mechanical movement over lead90 by lead 91 to oscillator means 93 which is an oscillator circuitboard within a housing. An oscillator cable 95 connects sensor 53through connector 42 (FIG. 6a) to oscillator means 93. Each sensor willhave a similar connector to oscillator means 93. The oscillator means 93contain all of the oscillator components except for the tuned circuitinductor and capacitor (FIG. 6a). A separate oscillator means 93, 97,98, 99 (FIG. 8) is provided for each sensor 53, 100, 102, 104. Cablemeans connect each oscillator means 93, 97, 98, 99 to the electronicprocessor means through cables connected to contacts 101, 103, 105 (onenot shown) with an interposed analog-to-digital converter andmultiplexer contained in a separate enclosure (not shown in FIG. 8). Thetransducer may be electrically connected to any one of the oscillators93, 97, 98. In a manner to be described in detail hereinafter, thiselectrical signal will be employed in compensating a thickness readingso as to adjust for diameter changes.

Similarly, still referring to FIG. 7, if the container were at position70 on sensor 52 and were to deform the same, this would createcounter-clockwise rotation of linkage means 76 which would movetransducer element 86 downwardly in the direction of arrow F. It will beappreciated, therefore, that by use of this linkage means, deformationregardless of where it occurs along sensor 52 will be properly convertedto a corresponding electrical signal reflective of a change in containerdiameter. It will be appreciated that another beneficial aspect of theinvention is that a single displacement monitoring means, such astransducer element 86, can function through the mechanical linkage toprovide for compensating diameter change data on a non-round annularcontainer regardless of the position of the container with respect tothe sensor.

FIGS. 8 through 11 show additional details of the illustrated systemwhich contains four sensors 53, 100, 102, 104. Each sensor 53, 100, 102,104 has a back-up bar, such as 54, for example. The back-up bars arefixedly secured to posts 111, 113 (FIGS. 7-11). As a result, when one ofthe sensors is displaced by a container, all of the sensors will move inunison and cause responsive movement of linkage elements 60, 76, 85 andtransducer 84.

The sensors 52, 100, 102, 104 function through a capacitance changeproviding a signal which alters the frequency of an oscillator circuit.The circuit has two frequency determining components, i.e., capacitanceas presented by the sensor means and inductance which is provided by aninductor of fixed value. The sensor means function as plates of thecapacitor with the glass of the container acting as the dielectric. Thecapacitor and inductor form a tank circuit whose natural resonantfrequency is determined by the value of these components. As thecapacitance of the sensor means changes due to variations in wallthickness of the glass, a new resonant frequency results. This shift infrequency is related to the amount of change in glass thickness. It isdesirable that the mass of the sensor means be kept as low as possiblein order to permit the sensor assembly to be displaced in a rapid mannerresponsive to changes in contour of the non-circular container.Combining to contribute to this desired objective is selecting asuitable sensor means thickness which preferably may be 0.250 to 0.350inch. An appropriate sensor means material which may, for example, bepolypropylene or polycarbonate and a suitable resilient back-up materialwhich may be urethane foam. It is also desirable that only the minimumnecessary oscillator components be placed on the sensor means. Aflexible cable connects the sensor to the rest of the oscillator. Inthis design, therefore, only the capacitor and inductor are contained inthe sensor and the connecting cable need not be part of the tunedcircuit. This eliminates the need for critically calibrated cables andmakes the circuit substantially immune to problems with movement ortolerances of the cable. This results in improved accuracy andreliability of the measurements.

The linear position sensor or displacement monitoring means 84 (FIG. 7)monitors change of position in one of the sensors. This change isdirectly proportional to changes in diameter of the container beinginspected.

As shown in FIG. 7, oval container 46 is positioned with its major axisparallel to the direction of container translation (arrow C) with belt50 and sensor 52 in intimate contact with opposite sides of thecontainer 46. As the container 46 is rotated axially, it will benecessary to increase the spacing between belt 50 and sensor 52 in orderto accommodate the enlarged transverse dimension of the container. Meanssuch as spring means may be provided to permit resilient displacement ofthe belt 50 or sensor 52 while preserving the desired intimacy ofcontact between the container 46 and the adjacent belt 50 and sensor 52.A preferred way of accomplishing this is to provide a spring or springson the sensor assembly so as to permit movement of the sensor 52transversely to the direction of travel (arrow C) of the container 46.For example, an extension spring, such as spring 87 (FIG. 8) will be incontact with pivot pin 82 such that in its unflexed position, the sensor52 will be in the position shown in FIG. 7 with the minor axis of thecontainer transverse to the path of container travel. The spring 87 willnormally keep the sensors in its closest relationship with respect tothe belt 50 and will be urged transversely outwardly as the containerrotates axially to position larger diameter portions in contact with thesensors.

It will be appreciated that an oval container, such as an ellipticalcontainer, cannot be the subject of simple measurement across either theminor or major axis in order to determine diameter. The electronicprocessor means which may be a suitable microprocessor programmed in amanner which will be well known to those skilled in the art, employs anequivalent diameter for calculating correction factors to be applied tothe measured wall thickness of the container. The formulas are basedupon the approximate cross-section of the container.

The operator merely needs to enter the diameter of the calibrationstandard. The electronic processor checks the output signal from theposition sensor means 84 and calculates displacements for the particularcontainer position. This permits determination of the thicknesscorrection factor which is required. The electronic microprocessorpreferably contains a "look-up" table which contains thicknesscorrections corresponding to various displacements of the displacementmeans 84 so that there need not be a new calculation each time. Theelectronic processor means then applies the correction factorcorresponding to a particular measure displacement to correct thethickness measurement and provide an accurate measure of thickness whichis independent of the diameter of the particular portion of thenon-round annular container being measured. The left and rightelevational views, shown respectively in FIGS. 9 and 10, show a jar 110supported on conveyor 109 and made of a dielectric material in contactwith the sensors 52, 100, 102, 104.

Bracket 114 supports the transducer 84 (not shown in this view). Asshown in FIGS. 9 and 10, each sensor 52, 100, for example, isoperatively associated with oscillator means 120, 124 which haverespectively electrical leads 122, 126 which serve to carry theoscillator output voltage which corresponds to container thickness toprovide the same to the electronic processor means after passing throughan analog-to-digital converter and multiplexer.

Referring to FIG. 12, a further refinement of the invention will now beconsidered. In this embodiment, means are provided to enhance the rateat which containers can be inspected. The length of sensor L of theprior embodiment may be considered to extend between the two dashedlines 160, 162 shown in FIG. 12. The length L' of sensor 170 of theembodiment of FIG. 12 is substantially less than that of L. For example,the length of the sensor strip portion of sensor 170 will correspond tothe circumference of the portion of the container that it will contact.An additional length which may be about 11/2 inches on the upstream endand 1/2 inch on the downstream end may be provided to take care of theportion of the sensor which extends beyond the sensor strip. In thisembodiment, more than one container 172, 174, 176 is on conveyor 178simultaneously even though only one will be in contact with sensor means170 at a given time. It will be appreciated that the length L' of sensor170 is sufficiently long to permit the sensor to inspect the entirecircumference of a non-round container 172, 174, 176 which is movingtranslationally along container 178 and is also being subjected to axialrotation and being urged into intimate contact with the sensor means 170by means not shown. Star wheel 180 serves to, in time coordinatedfashion, release containers for movement on the conveyor in thedirection indicated by G. Downstream of the sensor means is container176 which is in contact with resiliently biased member 181 in order tofacilitate efficient movement of the rotating non-round container.Slowdown motor 184 drives two slowdown belts on slowdown arm 182. Thisserves to reduce the speed of the containers and position the containerin the center of conveyor 178 and urge the containers in the directionindicated by arrow H.

In respect of FIG. 12, it will be appreciated that element 181, whichfacilitates efficient discharge of containers, such as 176 and element186, which can be resiliently mounted, each operate independently of thesensor means 170 and can thereby facilitate the presence of more thanone container in the inspection area at one time, even though only onecontainer would be in contact with the sensor means 170 at a given time.Another advantage of this embodiment, as well as the embodiment of FIG.13, is that the use of reduced length sensors serve to reduce the massof the sensors which, in turn, makes them more sensitive to sensordisplacement by the containers.

FIG. 13 shows another embodiment of the invention wherein duplicateinspection assemblies 210, 212 each have, respectively, capacitivesensor means 214, 216 which may consist of a plurality of verticallyspaced sensors for inspecting non-round annular container 220. In thismanner, each inspection unit 210, 212 may inspect a certain number ofcircumferential points with the two of them in the aggregate inspectingthe number of circumferential points on the container desired to beinspected. The sensor means 214, 216 can be relatively short as each, inprinciple, need inspect only in the aggregate approximately 180° of thecircumference rather than having a single sensor as in the otherembodiments inspect substantially the entire circumference.

FIG. 14 illustrates, in general, the sequence of operations ininspecting non-round containers by the present invention. A series offour capacitive sensors 240, 242, 244, 246, all disposed on one side ofthe path of travel of containers being inspected, have output signalscorresponding to the thickness of the portion of the container which hasbeen measured introduced, respectively, into oscillators 250, 252, 254,256 which produces corresponding voltage signals containing thicknessinformation. All of these voltage signals from the oscillators 250, 252,254, 256 are introduced into multiplexer 260 from which they areselectively introduced through analog-to-digital converter 262 into theelectronic processor means which, in the form shown, is a computer 264.The computer 264, with the assistance of the multiplexer, calculatesthickness at the four elevations monitored at each circumferential pointbeing monitored by the sensors 240, 242, 244, 246 as the container issubjected to rotational and translational movement. In addition, theposition transducer 84 emits an electrical displacement voltage signalwhich enters multiplexer 260 and is converted to a digital pulse inanalog-to-digital converter 262 and is introduced into the computer 264.The computer contains a look-up table, which for a given diametercalibration previously set by the operator produces a diametercorrection factor corresponding to the displacement of each of thesensors 240, 242, 244, 246. The computer 264 the combines the calculatedcontainer thickness at a particular point with the adjustment factor andproduces a reliable and accurate thickness reading at the positionmonitored. This signal may be stored in computer 264 or may be deliveredto interfacing means 270 so as to provide a hard copy printout, amonitor display or to activate a reject mechanism (not shown), or visualor audible alarm, if desired.

Referring to FIG. 15, the method of the present invention will bediscussed in greater detail. In referring to FIG. 15, more details ofthe process of the present invention will be considered. During initialset up, based upon the approximate diameters involved in a non-roundannular container a look-up table has been selected based upon thecalibration process which is dependent upon the approximate diametersizes of the container such as the major and minor axes of an ovalcontainer. A suitable calibration adjustment for glass or plastic whichhave different dielectric constants may be made as by adjusting the gainof the circuitry. After inspection has occurred and the voltage signalsfrom the sensor means have been delivered to the electronic processorand compared with the desired thickness readings, a thickness value isdetermined. Also, the displacement value is received in the electronicprocessor and is compared with a value in the look-up table to get anappropriate correction value based upon the change in diameter asreflected through the displacement reading. The inspection ready block270 indicates that the data is available. It is delivered to the readdisplacement block 272 and the displacement correction 274 is foundthrough comparison with the look-up table. The calculated correctedthickness number 276 is then obtained and the output is linearized 278.The thickness result 280 is then saved. If there is no additional data290, through line 292, the existing results are reported at 294. Ifthere is additional data, it is delivered over lead 296 to the readdisplacement block 272 with additional processing occurring at thatpoint. This cycle is continued until the inspection of a given containeris completed after which the results may be stored, displayed oremployed to automatically reject a container which does not have athickness within the desired range.

While the preferred embodiment employs a single displaceable element foreach array of sensors, if desired, more could be employed.

In another aspect of the invention, the system may be employed with orwithout thickness measurement to detect variations in diameter of acontainer which is designed to be round in the region inspected or toprovide on-line measurement of container diameter regardless ofcontainer shape. The equipment and methods disclosed herein could beemployed for such a purpose by employing the diameter voltage signalreceived from transducer 84 to the electronic processing means 264 forconversion into an absolute diameter or for comparison with a desireddiameter and determining the amount of departure therefrom. The diameterinformation could be stored, enhanced, printed in hard copy, employed toactivate a reject mechanism, or employed to provide an on-line monitordisplay. If desired, the diameter measuring portions of the system couldbe provided as a separate system directed toward diameterdeterminations. In such diameter, the sensor means could be substitutedfor by container contacting means which could be of the same structuralconfiguration as the sensor means, but would not require the capacitivecomponents. In the alternative, one or more elongated containercontacting members which would displace the transducer 84 throughintermediate linkage means, which could be of the type disclosed, couldbe employed. For inspection of non-round containers, resilient mountingof the container contacting means should be employed.

It will be appreciated that in some embodiments of the invention, suchas that shown in FIG. 13, for example, sensors will be provided on bothsides of the path of container travel. This is true regardless ofwhether one is employing the thickness measurement embodiment or theembodiment which is employed to measure diameter independent of athickness determination. As is disclosed in connection with FIGS. 7 and8, resilient means, such as spring 87, are employed to establishrelative movement between the sensor means on one side of the path ofcontainer travel and either (a) the means for urging the containers intocontact with the sensor means, or (b) a second set of sensor meansdisposed on the opposite side of the path. This relative movement can beestablished by either movement of sensor means on one side or movementof the container urging means or second sensor of sensor means. In thealternative, movement of both the sensor means on one side of the pathand either the (a) container urging means, or (b) second set of sensormeans on the other side of the path may be employed to effect suchrelative movement. This relative movement provides for adjustment ofrelative spacing to accommodate differences in the containers transversedimension as a non-round container rotates axially while preserving thedesired intimacy of contact with the container.

It will be appreciated that the apparatus and method of the presentinvention facilitates efficient, rapid reliable inspection at high speedof a large number of non-round containers composed of dielectricmaterial. This is accomplished without having to rely on a samplingtechnique. The system automatically compensates for changes in diameterof the various portions that sequentially contact the capacitive sensormeans. The invention may also be employed to inspect containers forvariations in diameter within a container and to provide on-linediameter measurement.

While it will be appreciated that emphasis has been placed herein, forconvenience of disclosure, on glass and plastic bottles, the inventionis not so limited and may be employed on glass or plastic jars and othercontainers composed entirely or partially of dielectric material. Thechoice of material would involve an initial calibration keyed to thematerial as the glass and plastic, for example, have differentdielectric properties, however, the system will function essentially thesame once the calibration has been accomplished.

Whereas particular embodiments of the invention have been describedabove, for purposes of illustration, it will be evident to those skilledin the art that numerous variations of the details may be made withoutdeparting from the invention as defined in the appended claims.

We claim:
 1. Apparatus for inspecting non-round containerscomprisingelongated capacitive sensor means, means for urging saidnon-around containers into intimate rotational contact with said sensormeans, means for effecting translational movement of said containersalong said sensor means, oscillator means operatively associated withsaid sensor means to receive thickness information in the form ofchanges in capacitance and for generating corresponding voltage signals,electronic processor means for receiving said voltage signals from saidoscillator means and comparing them with desired thickness values indetermining whether the desired thickness is present, displaceable meansoperatively associated with said sensor means for being displacedresponsive to variations in container diameter and emitting a responsivedisplacement electrical signal to said electronic processor meanscorresponding to the diameter of the portion of said container incontact with said sensing means, and said electronic processor meanshaving means for correcting said voltage signals for diameter variationsprior to effecting said comparison with desired thickness values inorder to provide a thickness value corrected for container diameter. 2.The inspection apparatus of claim 1 includingsaid electronic processormeans having a look-up table for determining a correction factor for asaid displacement to be employed in providing said corrected thicknessvalue.
 3. The inspection apparatus of claim 2 includingsaid electronicprocessor means having means for linearizing said corrected thicknessvalue.
 4. The inspection apparatus of claim 3 includingmeans forrepeating said thickness determination adjusted for container diametervariations as said container rotates along said sensor means.
 5. Theinspection apparatus of claim 4 includingsaid means for repeating saidthickness determination being adapted to provide progressively athickness reading for substantially the entire circumference of thecontainer.
 6. The inspection apparatus of claim 2 includingsaiddisplaceable means including transducer means acting responsive tomovement of said sensor means through container contact with said sensormeans.
 7. The inspection apparatus of claim 6 includingsaid displaceablemeans having linkage means fixedly secured to said sensor means on thereverse side of the sensor from the side which contacts said containers.8. The inspection apparatus of claim 7 includingsaid displaceable meansbeing secured to said sensor means at a first location and at a secondlocation spaced longitudinally along the sensor means therefrom, saiddisplaceable means having first rotatable linkage means operativelyassociated with said sensor at said first location and being rotatableresponsive to displacement of said sensor by a said container and secondrotatable linkage means operatively associated with said sensor means atsaid second location and being rotatable responsive to displacement ofsaid sensor by a said container, and linkage means connecting said firstrotatable linkage and said second rotatable linkage, whereby rotation ofsaid first rotatable linkage means or said second rotatable linkagemeans will establish responsive rotation of the other said first orsecond linkage means, and said transducer means being displacedresponsive to movement of either said first rotatable linkage means orsaid second rotatable linkage means and emitting correspondingdisplacement voltage signals.
 9. The inspection apparatus of claim 8includingmeans for delivering said displacement electrical signals tosaid electronic processor means.
 10. The inspection apparatus of claim 6includingsaid sensor means including at least one elongated sensororiented generally parallel to the path of travel of said containerthrough said inspection apparatus.
 11. The inspection apparatus of claim10 includingsaid sensor means including a plurality of generallyparallel relatively vertically spaced said sensors.
 12. The inspectionapparatus of claim 10 includingsaid means for urging said containersbeing on the opposite side of the path of travel of said containers fromsaid sensor means.
 13. The inspection apparatus of claim 8 includingsaidfirst rotatable linkage means and said second rotatable linkage meanseach having a first section connected to the rear of said sensor means,a second section fixed for rotation of said rotatable means thereaboutand a third section connected to said linkage means.
 14. The inspectionapparatus of claim 13 includingsaid first rotatable linkage means andsaid second rotatable linkage means each being generally triangular inshape.
 15. The inspection apparatus of claim 8 includingmultiplexermeans for receiving said voltage signals from said oscillator means andsaid displacement electrical signals from said transducer means andconverter means for receiving said voltage signals and said displacementelectrical signals and creating corresponding digital pulses fordelivery to said electronic processor means.
 16. The inspectionapparatus of claim 1 includingsaid non-round containers being generallyoval shaped, and said electronic processor means having means forprocessing oval container thickness values.
 17. The inspection apparatusof claim 16 includingsaid means for processing oval container valueshaving means for processing elliptical container values.
 18. Theinspection apparatus of claim 1 includingemploying first sensor meansdisposed on a first side of the path of travel of said containers andsecond sensor means disposed on the other side of said container path oftravel such that said first sensor means can determine the diameter ofportions of the circumference of said container and said second sensormeans can determine the diameter of other portions of the circumferenceof said container to thereby facilitate circumferential diametermeasurements while requiring rotation of the container for about 180°.19. The inspection apparatus of claim 1 includingresilient means forfacilitating resiliently maintained contact of said means for urging andsaid sensor means with said non-round containers while said containersare being subjected to axial rotation.
 20. The inspection apparatus ofclaim 19 includingsaid resilient means being operatively associated withat least one of (a) said means for urging and (b) said sensor means. 21.The inspection apparatus of claim 20 includingsaid resilient means beingoperatively associated with both said means for urging and said sensormeans.
 22. The inspection apparatus of claim 18 includingresilient meansfor facilitating resiliently maintained contact of said first sensormeans and said second sensor means with said non-round containers whilesaid containers are being subjected to axial rotation.
 23. Theinspection apparatus of claim 22 includingsaid resilient means includingspring means for facilitating resilient movement of said first andsecond sensor means generally transversely to the direction of travel ofsaid containers.
 24. The inspection apparatus of claim 23 includingsaidresilient means being operatively associated with at least one of saidfirst sensor means and said second sensor means.
 25. The inspectionapparatus of claim 24 includingsaid resilient means being operativelyassociated with both said first sensor means and said second sensormeans.
 26. The inspection apparatus of claim 19 includingsaid resilientmeans including spring means for facilitating resilient movement of saidsensor means generally transversely to the direction of travel of saidcontainers.
 27. The inspection apparatus of claim 10 includingsaidsensor means including on one side of said elongated sensor aresiliently mounted independent entry element and on the other side ofsaid sensor a resiliently mounted exit element which facilitate entryand exit of containers from said sensor area.
 28. Apparatus forinspecting containers comprisingelongated container contacting means,means for urging said containers into intimate contact with saidcontainer contacting means, means for effecting translational movementof said containers along said container contacting means, electronicprocessor means having means for receiving signals related to containerdiameter and converting the same into a container diameter measurement,and displaceable means operatively associated with said containercontacting means for being displaced responsive to variations incontainer diameter and emitting a responsive displacement electricalsignal to said electronic processor means corresponding to the diameterof the portion of said container in contact with said containercontacting means.
 29. The inspection apparatus of claim 28 includingsaidelectronic processor means having a look-up table for determining saiddiameter from said displacement electrical signals.
 30. The inspectionapparatus of claim 29 includingmeans for repeating said diameterdetermination as said container rotates along said container contactingmeans.
 31. The inspection apparatus of claim 30 includingsaiddisplaceable means including transducer means acting responsive tomovement of said container contacting means through container contactwith said container contacting means.
 32. The inspection apparatus ofclaim 31 includingsaid displaceable means having linkage means fixedlysecured to said container contacting means on the reverse side from theside which contacts said containers.
 33. The inspection apparatus ofclaim 32 includingsaid displaceable means being secured to saidcontainer contacting means at a first location and at a second locationspaced longitudinally along the container contacting means therefrom,said displaceable means having first rotatable linkage means operativelyassociated with said container contacting means at said first locationand being rotatable responsive to displacement of said containercontacting means by a said container and second rotatable linkage meansoperatively associated with said container contacting means at saidsecond location and being rotatable responsive to displacement of saidcontainer contacting means by a said container, linkage means connectingsaid first rotatable linkage and said second rotatable linkage, wherebyrotation of said first rotatable linkage means or said second rotatablelinkage means will establish responsive rotation of the other said firstor second linkage means, and said transducer means being displacedresponsive to movement of either said first rotatable linkage means orsaid second rotatable linkage means and emitting correspondingdisplacement voltage signals.
 34. The inspection apparatus of claim 33includingmeans for delivering said displacement electrical signals tosaid electronic processor means.
 35. The inspection apparatus of claim30 includingsaid container urging means and said container contactingmeans being relatively resiliently movable so as to maintain intimatecontact with a non-round said container disposed therebetween.
 36. Theinspection apparatus of claim 35 includingresilient means for relativelypositioning said container urging means and said container contactingmeans a distance generally equal to the smallest diameter of saidcontainer and for resiliently yielding as said container is rotatedaxially.
 37. The inspection apparatus of claim 36 includingsaidresilient means including spring means operatively associated with saidcontainer contacting means.
 38. The inspection apparatus of claim 30includingsaid apparatus being structured to inspect containers which areround in the region being inspected.
 39. The inspection apparatus ofclaim 36 includingsaid resilient means resiliently mounting at least oneof said (a) container urging means and (b) said container contactingmeans.
 40. The inspection apparatus of claim 39 includingsaid resilientmeans resiliently mounting both said (a) container urging means and (b)said container contacting means.
 41. The inspection apparatus of claim28 includingfirst said container contacting means disposed on one sideof the path of travel of said containers and second said containercontacting means disposed on the other side of said path, and resilientmeans operatively associated with at least one of (a) said firstcontainer contacting means and (b) said second container contactingmeans to facilitate relative movement therebetween.
 42. The inspectionapparatus of claim 41 includingsaid resilient means being operativelyassociated with both said first and second container contacting means.